Inositol Polyphosphates and HIV-1 Maturation

项目总结/摘要 HIV-1是获得性免疫缺陷综合征（AIDS）的病原体，其复制涉及免疫缺陷病毒（HIV-1）。 由Gag多聚蛋白组成的未成熟颗粒的组装和这些颗粒的随后成熟 通过蛋白水解裂解。虽然HIV-1感染可以通过明智的预防措施得到有效控制， 在施用抗病毒药物的情况下，治疗不是治愈性的，并且耐药性是持续关注的问题。公理上， HIV-1在其复制周期的每个阶段都依赖于与宿主细胞分子的相互作用。虽然许多 这些病毒-宿主相互作用发生在蛋白质、宿主细胞代谢物肌醇六磷酸（IP 6） 最近作为参与HIV-1复制的关键宿主分子出现。IP 6似乎与Gag 在感染的细胞中的多聚蛋白，从而稳定Gag六聚体晶格和促进病毒体组装。 值得注意的是，IP 6还在体外与切割的病毒CA蛋白结合，并促进CA自组装成锥状结构。 这些结构在形态上与天然HIV-1衣壳相似。根据这些观察，一个模型 其中在HIV-1感染期间，当病毒蛋白酶裂解Gag晶格时释放IP 6 成熟IP 6的释放允许其与组装的CA六聚体结合，从而稳定成熟衣壳 晶格在这个项目中，我们将验证这个模型的关键预测。采用新的和敏感的测定方法， 定量与纯化的亚病毒复合物相关的IP 5和IP 6的水平，我们将确定特异性的 这些配体从未成熟的Gag晶格中解离所需的Gag多蛋白中的裂解。 其次，我们将确定IP 6与成熟衣壳晶格结合的分子决定因素，包括测试 Arg 18在CA中的作用，其已显示在体外与IP 6形成离子相互作用。最后，我们将量化 不同逆转录病毒颗粒中存在的IP 6水平是了解逆转录病毒范围的第一步。 逆转录病毒在其复制周期中利用IP 6。IP 6是第一种非核苷酸宿主细胞代谢物， HIV-1复制已被证明依赖于。定义IP 6在HIV-1成熟中的作用机制是 这对于理解HIV-1如何利用这种新的病毒-宿主相互作用至关重要。最终，该项目可能会导致 开发新的抗病毒药物，从而扩大长期可用的治疗选择 HIV-1感染的管理。

Project Summary/Abstract Replication of HIV-1, the causative agent of Acquired Immune Deficiency Syndrome (AIDS), involves the assembly of immature particles composed of the Gag polyprotein and subsequent maturation of these particles by proteolytic cleavage. Although HIV-1 infection can be effectively controlled through the judicious administration of antiviral drugs, therapy is not curative, and drug resistance is a constant concern. Axiomatically, HIV-1 depends on interactions with host cell molecules at every stage of its replication cycle. Although many of these virus-host interactions occur between proteins, the host cell metabolite inositol hexakisphosphate (IP6) has recently emerged as a key host molecule involved in HIV-1 replication. IP6 appears to bind to the Gag polyprotein in infected cells, thus stabilizing the Gag hexameric lattice and promoting virion assembly. Remarkably, IP6 also binds to the cleaved viral CA protein in vitro and promotes CA self-assembly into cone- like structures that are morphologically similar to native HIV-1 capsids. Based on these observations, a model has been proposed in which IP6 is released upon cleavage of the Gag lattice by the viral protease during HIV-1 maturation. Release of IP6 permits its binding to assembling CA hexamers, thus stabilizing the mature capsid lattice. In this project, we will validate key predictions of this model. Employing novel and sensitive assays to quantify the levels of IP5 and IP6 associated with purified subviral complexes, we will identify the specific cleavages in the Gag polyprotein required for dissociation of these ligands from the immature Gag lattice. Second, we will identify the molecular determinants of IP6 binding to the mature capsid lattice, including testing the role of Arg18 in CA that has been shown to form ionic interactions with IP6 in vitro. Finally, we will quantify the levels of IP6 present in particles of diverse retroviruses as a first step in understanding the range of retroviruses that utilize IP6 in their replication cycles. IP6 is the first non-nucleotide host cell metabolite on which HIV-1 replication has been shown to depend. Defining the mechanism of IP6 action in HIV-1 maturation is essential to understand how HIV-1 exploits this novel virus-host interaction. Ultimately, the project may lead to the development of new antiviral drugs, thus expanding the available therapeutic options for the long-term management of HIV-1 infection.